1. Field of the Invention
The present invention relates to a heat-shrinkable cylindrical label which is attached to a container or the like by heat shrinkage, and a method of producing a longitudinal cylindrical label continuum wherein the cylindrical label is continuously extend sectioned.
2. Background Art
Heat-shrinkable cylindrical labels (shrinkable labels each formed into a cylindrical form) are used in the state that they are attached to containers such as drink bottles or cosmetic containers.
Such a heat-shrinkable cylindrical label is made of a label substrate which has a sheet (generally called a film in some cases) made of a synthetic resin and having heat shrinkability. Both side end sections of this label substrate are overlapped with each other, and the overlapped portions are stuck onto each other, thereby forming a center seal section.
As this label substrate, there are used substrates of various kinds, examples of which include not only a substrate having a mono-layered structure of a sheet having heat shrinkability but also a substrate having a laminated structure wherein two or more sheets are laminated. As an example wherein a laminate is used as a label substrate, Japanese Patent Application Laid-Open (JP-A) No. 8-106252 describes a heat-shrinkable cylindrical label wherein a label substrate which comprises a heat-shrinkable sheet (represented as a heat-shrinkable film in the same publication) and a foamed resin sheet (represented as a heat-shrinkable foamed sheet in the publication) laminated onto the heat-shrinkable sheet is made into a cylindrical form, and then a center seal section is formed. In this heat-shrinkable cylindrical label, the laminated foamed resin sheet has heat insulating effect. Accordingly, even if a container or the like to which this cylindrical label is attached is heated or cooled, the heat of the container or the like is not easily conducted to the user. Thus, the label is a preferred label.
The structure of a center seal section of such a heat-shrinkable cylindrical label, which is made of a laminate, is described in the above-mentioned publication. Specifically, the following structures are disclosed: as illustrated in FIG. 20(a) attached, a structure wherein the rear face of a foamed resin sheet 102 at one side end section 103a of the laminate is overlapped with the front face of a heat-shrinkable sheet 101 at the other side end section 103b, and the overlapped faces are stuck onto each other through an adhesive 105; and as illustrated in FIG. 20(b), a structure wherein the rear face of a foamed resin sheet 102 at one side end section 103a is overlapped with the front face of a heat-shrinkable sheet 101 at the other side end section 103b, and the overlapped faces are stuck onto each other with a tape 106.
However, when the rear face of the one side end section 103a of the label substrate 103 is overlapped with the front face of the other side end section 103b and the faces are stuck to each other through the adhesive 105, portions of the foamed resin sheet 102 are overlapped with each other in the vertical direction in the resultant center seal section so that the center seal section becomes very thick. As a result, when the cylindrical label continuum wherein the cylindrical label is continuously extended is wound into a roll form, there is caused a problem that the length of the winding becomes short. Furthermore, after the cylindrical label is attached to a container or the like by heat shrinkage, a site which partially swells into a large thickness is generated in the longitudinal direction of the cylindrical label.
The structure shown in FIG. 20(a) also has a problem that: the adhesive 105 is coated onto the foamed resin sheet 102; thus, if the amount of the adhesive is small, a sufficient adhesive strength is not obtained at ease. Additionally, the side edge of the foamed resin layer becomes oblique so as to be exposed to the outside when this label is attached to a product by shrinkage. For this reason, the external appearance of the product to which the label is attached is bad.
About a label having portions stuck to each other with a tape, as illustrated in FIG. 20(b), at the time of performing center sealing, it is essential to adjust or match tensile tensions or forwarding-timings of a tape 106 and a label substrate 103 skillfully. Thus, the adjustment is complicated.
These matters are not problems limited to laminates wherein a foamed resin sheet is laminated onto a heat-shrinkable sheet. For example, similar problems are caused in the case of using a label substrate wherein a nonwoven cloth, Japanese paper or the like is laminated. Furthermore, when the material of a heat-shrinkable sheet is different from that of a foamed resin sheet or nonwoven cloth, the two may be unable to be stuck to each other with a solvent.
The present invention has been made in order to provide: a heat-shrinkable cylindrical label comprising an inner layer sheet laminated onto the rear face of an outer layer sheet, the label being characterized by being improved in such a manner that its center seal section does not become thick; and a method of producing this cylindrical label continuum. A further object of the invention is to provide a heat-shrinkable cylindrical label which exhibits a beautiful external appearance after this label is attached to a product by shrinkage.